Pope Leo XIII on the Holy Spirit

" At least there are certainly many who are very deficient in their religious practices, but their faith is involved in much darkness. Wherefore all preachers and those having care of souls should remember that it is their duty to instruct their people more diligently and more fully about the Holy Ghost - avoiding, however, difficult and subtle controversies, and eschewing the dangerous folly of those who rashly endeavour to pry into divine mysteries. What should be chiefly dwelt upon and clearly explained is the multitude and greatness of the benefits which have been bestowed, and are constantly bestowed, upon us by this Divine Giver, so that errors and ignorance concerning matters of such moment may be entirely dispelled, as unworthy of "the children of light." ".

Pope Leo XIII - "Encyclical Divinum Illud Munus" - May 9, 1897 - 1987